1. Field of the Invention
The present invention relates to the field of rotating machinery and the monitoring of such machinery for defects, breakages and the like. More particularly, the invention relates to a system for monitoring a pulley assembly or other rotating machine element and for detecting a change in the operating condition of the assembly by reference to a vibration or load profile.
2. Description of the Related Art
A variety of industrial, mining and other applications exist for rotating machinery. Such machinery includes drive systems and material handling systems, such as conveyors and the like. Many such rotating machinery systems are periodically subjected to considerable loading that may result in latent defects or, in severe cases, catastrophic failure. In many cases, eventual failure is the result of continued cycling of machine elements in which defects have already occurred. Such defects may including cracks, tears, or other deformations in the mechanical structures that will eventually fail, even under normal working stresses. Because the failure of such machinery may lead to expensive repairs and down time, it is important to locate latent defects as early as possible to permit scheduling of necessary repairs before failures occur.
Failures due to latent defects are particularly problematic in conveyor and drive systems. Such systems, omnipresent in many industrial, mining, timber products, shipping and power generating facilities, to name just a few, are necessary for the transport of raw and processed materials. The systems typically include pulleys and rollers that directly contact the transported material, or that support conveyor belts or chains on which the transported material is deposited. In many applications, loads are quite substantial and the machinery must remain functional virtually at all times. Failure of elements of the machinery, particularly of pulleys and rollers, results in unscheduled repairs to bring the machinery back into service. Where the pulleys and rollers support a conveyor belt or chain, the belt may need to be removed to give access to the failed component, resulting in additional down time and expense.
Certain serious or obvious defects in rotating machine systems may be detectable by operations personnel based upon auditory or visual inspection. However, many defects escape such detection due to their latent nature or location. In conveyor systems in particular, certain rotating machinery may be located on booms, towers and the like, where physical inspection is very difficult. While some latent defects may be discoverable upon close inspection during machine servicing, for much critical machinery, such servicing is generally rare and must be minimized. Moreover, many latent defects are not readily discoverable even upon close visual inspection, without recourse to special equipment which is not typically available in industrial and other settings.
There is a need, therefore, for an improved technique for the early detection of defects in rotating machine systems. In particular, there is a need for a system for detecting such defects that can be applied on existing structures as well as new installations, and that can provide a reliable indication of a potential defect during operation of the machinery.